const DataLayout *DL;
private:
+ bool isDenselyPacked(Type *type);
+ bool canPaddingBeAccessed(Argument *Arg);
CallGraphNode *PromoteArguments(CallGraphNode *CGN);
bool isSafeToPromoteArgument(Argument *Arg, bool isByVal) const;
CallGraphNode *DoPromotion(Function *F,
- SmallPtrSet<Argument*, 8> &ArgsToPromote,
- SmallPtrSet<Argument*, 8> &ByValArgsToTransform);
+ SmallPtrSetImpl<Argument*> &ArgsToPromote,
+ SmallPtrSetImpl<Argument*> &ByValArgsToTransform);
+
+ using llvm::Pass::doInitialization;
bool doInitialization(CallGraph &CG) override;
/// The maximum number of elements to expand, or 0 for unlimited.
unsigned maxElements;
return Changed;
}
+/// \brief Checks if a type could have padding bytes.
+bool ArgPromotion::isDenselyPacked(Type *type) {
+
+ // There is no size information, so be conservative.
+ if (!type->isSized())
+ return false;
+
+ // If the alloc size is not equal to the storage size, then there are padding
+ // bytes. For x86_fp80 on x86-64, size: 80 alloc size: 128.
+ if (!DL || DL->getTypeSizeInBits(type) != DL->getTypeAllocSizeInBits(type))
+ return false;
+
+ if (!isa<CompositeType>(type))
+ return true;
+
+ // For homogenous sequential types, check for padding within members.
+ if (SequentialType *seqTy = dyn_cast<SequentialType>(type))
+ return isa<PointerType>(seqTy) || isDenselyPacked(seqTy->getElementType());
+
+ // Check for padding within and between elements of a struct.
+ StructType *StructTy = cast<StructType>(type);
+ const StructLayout *Layout = DL->getStructLayout(StructTy);
+ uint64_t StartPos = 0;
+ for (unsigned i = 0, E = StructTy->getNumElements(); i < E; ++i) {
+ Type *ElTy = StructTy->getElementType(i);
+ if (!isDenselyPacked(ElTy))
+ return false;
+ if (StartPos != Layout->getElementOffsetInBits(i))
+ return false;
+ StartPos += DL->getTypeAllocSizeInBits(ElTy);
+ }
+
+ return true;
+}
+
+/// \brief Checks if the padding bytes of an argument could be accessed.
+bool ArgPromotion::canPaddingBeAccessed(Argument *arg) {
+
+ assert(arg->hasByValAttr());
+
+ // Track all the pointers to the argument to make sure they are not captured.
+ SmallPtrSet<Value *, 16> PtrValues;
+ PtrValues.insert(arg);
+
+ // Track all of the stores.
+ SmallVector<StoreInst *, 16> Stores;
+
+ // Scan through the uses recursively to make sure the pointer is always used
+ // sanely.
+ SmallVector<Value *, 16> WorkList;
+ WorkList.insert(WorkList.end(), arg->user_begin(), arg->user_end());
+ while (!WorkList.empty()) {
+ Value *V = WorkList.back();
+ WorkList.pop_back();
+ if (isa<GetElementPtrInst>(V) || isa<PHINode>(V)) {
+ if (PtrValues.insert(V))
+ WorkList.insert(WorkList.end(), V->user_begin(), V->user_end());
+ } else if (StoreInst *Store = dyn_cast<StoreInst>(V)) {
+ Stores.push_back(Store);
+ } else if (!isa<LoadInst>(V)) {
+ return true;
+ }
+ }
+
+// Check to make sure the pointers aren't captured
+ for (StoreInst *Store : Stores)
+ if (PtrValues.count(Store->getValueOperand()))
+ return true;
+
+ return false;
+}
+
/// PromoteArguments - This method checks the specified function to see if there
/// are any promotable arguments and if it is safe to promote the function (for
/// example, all callers are direct). If safe to promote some arguments, it
isSelfRecursive = true;
}
+ // Don't promote arguments for variadic functions. Adding, removing, or
+ // changing non-pack parameters can change the classification of pack
+ // parameters. Frontends encode that classification at the call site in the
+ // IR, while in the callee the classification is determined dynamically based
+ // on the number of registers consumed so far.
+ if (F->isVarArg()) return nullptr;
+
// Check to see which arguments are promotable. If an argument is promotable,
// add it to ArgsToPromote.
SmallPtrSet<Argument*, 8> ArgsToPromote;
Type *AgTy = cast<PointerType>(PtrArg->getType())->getElementType();
// If this is a byval argument, and if the aggregate type is small, just
- // pass the elements, which is always safe. This does not apply to
- // inalloca.
- if (PtrArg->hasByValAttr()) {
+ // pass the elements, which is always safe, if the passed value is densely
+ // packed or if we can prove the padding bytes are never accessed. This does
+ // not apply to inalloca.
+ bool isSafeToPromote =
+ PtrArg->hasByValAttr() &&
+ (isDenselyPacked(AgTy) || !canPaddingBeAccessed(PtrArg));
+ if (isSafeToPromote) {
if (StructType *STy = dyn_cast<StructType>(AgTy)) {
if (maxElements > 0 && STy->getNumElements() > maxElements) {
DEBUG(dbgs() << "argpromotion disable promoting argument '"
// Now check every path from the entry block to the load for transparency.
// To do this, we perform a depth first search on the inverse CFG from the
// loading block.
- for (BasicBlock *P : predecessors(BB)) {
- for (idf_ext_iterator<BasicBlock*, SmallPtrSet<BasicBlock*, 16> >
- I = idf_ext_begin(P, TranspBlocks),
- E = idf_ext_end(P, TranspBlocks); I != E; ++I)
- if (AA.canBasicBlockModify(**I, Loc))
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
+ BasicBlock *P = *PI;
+ for (BasicBlock *TranspBB : inverse_depth_first_ext(P, TranspBlocks))
+ if (AA.canBasicBlockModify(*TranspBB, Loc))
return false;
}
}
/// arguments, and returns the new function. At this point, we know that it's
/// safe to do so.
CallGraphNode *ArgPromotion::DoPromotion(Function *F,
- SmallPtrSet<Argument*, 8> &ArgsToPromote,
- SmallPtrSet<Argument*, 8> &ByValArgsToTransform) {
+ SmallPtrSetImpl<Argument*> &ArgsToPromote,
+ SmallPtrSetImpl<Argument*> &ByValArgsToTransform) {
// Start by computing a new prototype for the function, which is the same as
// the old function, but has modified arguments.
// Patch the pointer to LLVM function in debug info descriptor.
auto DI = FunctionDIs.find(F);
- if (DI != FunctionDIs.end())
- DI->second.replaceFunction(NF);
-
+ if (DI != FunctionDIs.end()) {
+ DISubprogram SP = DI->second;
+ SP.replaceFunction(NF);
+ FunctionDIs.erase(DI);
+ FunctionDIs[NF] = SP;
+ }
+
DEBUG(dbgs() << "ARG PROMOTION: Promoting to:" << *NF << "\n"
<< "From: " << *F);
// of the previous load.
LoadInst *newLoad = new LoadInst(V, V->getName()+".val", Call);
newLoad->setAlignment(OrigLoad->getAlignment());
- // Transfer the TBAA info too.
- newLoad->setMetadata(LLVMContext::MD_tbaa,
- OrigLoad->getMetadata(LLVMContext::MD_tbaa));
+ // Transfer the AA info too.
+ AAMDNodes AAInfo;
+ OrigLoad->getAAMetadata(AAInfo);
+ newLoad->setAAMetadata(AAInfo);
+
Args.push_back(newLoad);
AA.copyValue(OrigLoad, Args.back());
}
projects / oota-llvm.git / blobdiff